In the majority of screen printing operations, more than one color is used to create the desired image. The use of more than one color results in using several screens, one for each color, wherein each screen has the associated image for that color. It is therefore necessary to ensure that the images from each screen align properly so that the associated colors align properly. This is typically done by ensuring that the screen is properly aligned in the frame and aligning the frame to a platform which receives the article that is to receive the image.
One convention is to attach the rigid frame to a screen holder, wherein the screen holder has a stationary bar and a moveable bar that pivots up and down relative to the stationary bar. At the end of that moveable bar is located a U-shaped print head or frame holder channel. The U-shaped channel has a pair of operating screws with swivel heads that rotate to engage the frame. The frame moves with the moveable bar downward in proximity with the article and the platform to align the image on the screen with the article so that the image may be transferred to the article. It is a trial and error process to align the frame in the U-shaped channel to achieve proper alignment.
Tensioning frames replace the rectangular sides of the frame with tensioning rollers. The curved rollers create a difficult surface to secure the screen holder for proper alignment. One design to overcome this problem is a tensioning frame that has three tensioning rollers and a square side which is not adjustable. Furthermore, to achieve the desired result from high tension screens, the frame must be tensioned periodically. The use of one square non-rotatable side does not achieve all the benefits of tour tension sides.
It is desired to have a registration means that allows easy accurate alignment and in addition allows several different frames to be received without changes to a registration bar.